This invention relates to a method and a device for use in simulating a change in color of a color domain of an object or material body.
Computer-aided design (CAD) is applicable to color design. It becomes often necessary on carrying out the color design to simulate a color change from an original color to a different color at a color domain of an object. The computer-aided design makes it possible to evaluate the color change without actually manufacturing the object with the original color varied in various manners at the color domain.
By way of example, let it be assumed that a color arrangement should be designed for a body of an automobile with the automobile used as the object and with the body used as the color domain and that the color domain is formed with a single original color. Under the circumstances, simulation may be carried out as follows.
A color television camera is used at first to pick up the object to produce an original color television signal representative of a colored original image of the object. A color cathode-ray tube is used to visually display the image. Subsequently, a computer system is used to deal with the television signal and to produce a changed color television signal which represents the image with the original color changed in various manners at the color domain.
For use in simulating a color change, a device is proposed in a paper contributed by Osami Maeda, Akihiko Ooe, and Masaki Fuse in Japanese to a technical periodical named "Sen'i to Kogyo" (Textiles and Industry), Volume 36 (1980), No. 6, pages 195 to 199, under the title of "Haisyoku Simyuresyon Soti" (Device for Simulating Color Arrangement). In the manner which will later be described a little more in detail, the device may be effective in designing a color arrangement of either a woven fabric or the interior of a room. The device is, however, incapable of faithfully simulating a color distribution on a curved surface.
On the other hand, shading in computer graphics is discussed in an article contributed by Bui Tuong Phong to "Communications of the ACM," Volume 18, No. 6 (June 1975), pages 311 to 317, under the title of "Illumination for Computer Generated Pictures." According to the Bui Tuong Phong article, excellent shaded graphic displays are obtained not only for curved surfaces but also for objects made of transparent materials. The computer generated displays are, however, not applicable to colored objects directly as they stand.